Merge pull request #16931 from taosdata/fix/3.0_bugfix_wxy

enh: the expression in project is pushed down to scan

source/libs/planner/src/planSpliter.c

@@ -915,20 +915,30 @@ static int32_t stbSplSplitSortNode(SSplitContext* pCxt, SStableSplitInfo* pInfo)
 }
 
 static int32_t stbSplSplitScanNodeWithoutPartTags(SSplitContext* pCxt, SStableSplitInfo* pInfo) {
-  int32_t code = splCreateExchangeNodeForSubplan(pCxt, pInfo->pSubplan, pInfo->pSplitNode, SUBPLAN_TYPE_MERGE);
+  SLogicNode* pSplitNode = pInfo->pSplitNode;
+  if (NULL != pInfo->pSplitNode->pParent && QUERY_NODE_LOGIC_PLAN_PROJECT == nodeType(pInfo->pSplitNode->pParent) &&
+      NULL == pInfo->pSplitNode->pParent->pLimit && NULL == pInfo->pSplitNode->pParent->pSlimit) {
+    pSplitNode = pInfo->pSplitNode->pParent;
+  }
+  int32_t code = splCreateExchangeNodeForSubplan(pCxt, pInfo->pSubplan, pSplitNode, SUBPLAN_TYPE_MERGE);
   if (TSDB_CODE_SUCCESS == code) {
     code = nodesListMakeStrictAppend(&pInfo->pSubplan->pChildren,
-                                     (SNode*)splCreateScanSubplan(pCxt, pInfo->pSplitNode, SPLIT_FLAG_STABLE_SPLIT));
+                                     (SNode*)splCreateScanSubplan(pCxt, pSplitNode, SPLIT_FLAG_STABLE_SPLIT));
   }
   ++(pCxt->groupId);
   return code;
 }
 
 static int32_t stbSplSplitScanNodeWithPartTags(SSplitContext* pCxt, SStableSplitInfo* pInfo) {
-  int32_t code = stbSplCreateMergeNode(pCxt, pInfo->pSubplan, pInfo->pSplitNode, NULL, pInfo->pSplitNode, true);
+  SLogicNode* pSplitNode = pInfo->pSplitNode;
+  if (NULL != pInfo->pSplitNode->pParent && QUERY_NODE_LOGIC_PLAN_PROJECT == nodeType(pInfo->pSplitNode->pParent) &&
+      NULL == pInfo->pSplitNode->pParent->pLimit && NULL == pInfo->pSplitNode->pParent->pSlimit) {
+    pSplitNode = pInfo->pSplitNode->pParent;
+  }
+  int32_t code = stbSplCreateMergeNode(pCxt, pInfo->pSubplan, pSplitNode, NULL, pSplitNode, true);
   if (TSDB_CODE_SUCCESS == code) {
     code = nodesListMakeStrictAppend(&pInfo->pSubplan->pChildren,
-                                     (SNode*)splCreateScanSubplan(pCxt, pInfo->pSplitNode, SPLIT_FLAG_STABLE_SPLIT));
+                                     (SNode*)splCreateScanSubplan(pCxt, pSplitNode, SPLIT_FLAG_STABLE_SPLIT));
   }
   pInfo->pSubplan->subplanType = SUBPLAN_TYPE_MERGE;
   ++(pCxt->groupId);